Test patch for diagnosing allergies



TEST PATCH FOR DIAGNOSING ALLERGIES Filed Aug. 196'? INVENTOR GUSTAV SIGFRID FREGERT his 4 ATTORNEYS.

United States Patent O 3,515,126 TEST PATCH FOR DIAGNOSING ALLERGIES Gustav Sigfrid Fregert, Planetgatan 19, Lund, Sweden Filed Aug. 4, 1967, Ser. No. 658,461 Claims priority, application Sweden, Aug. 11, 1966, 10,891/ 66 Int. Cl. A61b /00 U.S. Cl. 128--2 3 Claims ABSTRACT OF THE DISCLOSURE A test patch used in proving the presence or absence of particular contact enzymes includes an adhesive plaster carrier for the test patch which is made of a metal foil and is impervious to liquids and gases. A smaller absorbent test piece is attached to the carrier. When the test patch is attached to the skin the carrier maintains a free zone around the test piece in which the skin can not be contacted or affected by any adhesives. Substances applied to the test piece cannot escape through the impervious carrier.

The present invention relates to test patches, and, more particularly, to test patches used in providing the presence or absence of particular allergic contact eczemas.

Contact allergies are caused by skin contact with certain substances and result in a reaction by the skin producing an eczema. When a person has contracted a contact allergy for the certain substance, an eczema occurs each time his skin comes into contact With the actual substance, very small amounts of the substance being sufiicient to cause the occurrence of eczemas. The cause of a contact allergy is specific, i.e., it extends in the specific case only to one or only some particular substances.

Contact allergies afiiict people for long periods of time, often throughout their entire lives. For this reason, it is of utmost importance to find the exact substance or substances to which a person is allergic so that the products which contain the substance or substances in question may be avoided.

One method used in identifying the particular substance or substances which cause the occurrence of allergic contact eczemas on a persons skin involves the use of test patches from which so-called allergic patch test reactions are obtained.

Conventional test patches used for this purpose are composed of one or several liquid absorbing test pieces arranged on the sticky side of an adhesive plaster carrier. When used in an allergy test, a numbetr of such test pieces are provided with solutions of substances suspected of causing the allergic contact eczema. The test pieces are then applied on the patients skin by means of the adhesive plaster carrier. Conventional test patches, however, have many drawbacks. One drawback is that the plaster carriers are permeable, permitting the test substances absorbed by the test pieces partly or completely to pass out through the carriers, thus greatly limiting the effectiveness of the test patches in producing allergic contact eczemas. A second drawback of the plaster carriers used in conventional test patches is that the adhesive of the carrier adheres to the patients skin causing the occurrence of an erythema which is easily spread to the area of the skin covered by the test piece proper.

The above-mentioned drawbacks often cause a wrong diagnosis to be made. Test substances have been improperly identified as producing allergic contact eczemas as a result of the difliculty of distinguishing and determining the reaction of the test substance to the patients skin from that of the skin reaction to the adhesive mass on the carrier. Other erythema producing substances which 3,515,126 Patented June 2, 1970 "Ice have passed out through the carrier have been improperly eliminated due to their failure to produce an allergic patch test reaction.

Prior attempts to eliminate these drawbacks have included dividing the adhesive side of the carrier from the peripheral portions of the abutment surface of the test piece which contact the patients skin by a layer of viscose film or the like. Such attempts, however, have not been successful because the viscose film is not sufiiciently impermeable.

In accordance with the present invention, the carrier for the test patch includes or comprises a layer of material that is liquid and gas impervious.

In accordance with a preferred embodiment of the invention, the liquid and gas impervious layer in the carrier comprises an aluminum foil to which the test piece is attached via a plastic foil by heat sealing and without glue or adhesive.

The test patches in accordance with the present invention may be arranged on a continuous test strip compris ing a continuous web of a liquid and gas impervious material, preferably a metal foil, which forms the carrier. The test pieces are placed at spaced intervals along one side of this strip with each test piece being separated from every other test piece by means of apertures in the continuous web.

For a better understanding of the present invention reference may be had to the accompanying drawings in which:

FIG. 1 is a plan view of a test patch in accordance with the present invention;

FIG. 2 is an enlarged sectionalview through the test patch taken on line II-II of FIG. 1; and

FIG. 3 shows a test strip comprising a number of test patches arranged one after the other.

As shown in FIGS. 1 and 2 the test patch includes a laminated carrier 1 comprising a rectangular-shaped aluminum foil 2 covered on two sides by a plastic foil 3 and 4. One side of the aluminum foil 2 is connected by heat sealing via the plastic foil 3 to a paper foil 5 Without glue. A circular test piece 6 of a liquid absorbing material, as for example, blotting paper or filter paper, is connected by heat sealing via the plastic foil 4 to the opposite side of the aluminum foil 2 without glue, the borders 7 of the circular test piece 6 being situated at a distance from the side borders 8 of the rectangular-shaped aluminum foil 2 so as to form a free zone 9.

In use the test piece 6 is provided with a solution or Vaseline composition of a test substance suspected to cause allergic contact eczemas on the skin of the patient. The carrier 1 with test piece 6 attached is then applied to a suitable place on the patients skin. The carrier 1 is applied by means of an adhesive plaster attached to the opposite side of the metal foil, said plaster having an area larger than the test patch. The carrier 1, which is wider than the test piece 6, is then pressed with force against the patients skin along the carriers side borders 8 to obtain adherence with the skin so that the test piece 6 is enclosed in a hermetically closed chamber. The formation of a hermetically closed chamber increases the penetration of the test substance applied due to the humidity of the skin and prevents the test substance from passing out through the test patch. The carrier 1 with the attached test piece 6 is removed from the patients skin after about two days. If the test substance causes a contact allergy with the patients skin, a contact eczema in the form of an allergic patch test reaction will have occurred at the place where the test piece 6 with the actual test substance was in contact with the patients skin. The free zone 9 existing between the test piece 6 and the contact side of the plaster carrier 1 prevents the skin reaction to the test substance from being combined with the skin erythema easily caused by a surrounding glue or adhesive mass and also prevents any glue or adhesive from becoming dissolved in the test substance since, as mentioned above, connection of the test piece 6 and paper foil to the carrier 1 is via heat sealing plastic foils 3 and 5, and without the use of glue or adhesive.

As shown in FIG. 3, a number of test patches can be arranged to form a continuous strip or tape, the free zones 9 of the test patches being separated from each other by means of essentially rectangular apertures 10 arranged perpendicularly to the longitudinal direction of the strip such that two neighboring test patches are interconnected by means of two lateral connections 11 which are parallel to each other. By tearing the lateral connections 11, one may separate from the strip an arbitrary number of test patches as desired.

The test patches in accordance with the present invention my also be used in identifying toxic substances that irritate the patients skin even when these toxic substances do not produce a so-called contact allergy. While these toxic substances may irritate the patients skin without causing the skin to acquire the kind of receptivity necessary to produce an allergic contact eczema, these toxic substances can damage the skin of all persons if the contact is sufliciently intense and of long duration.

Many modifications can be made to the present invention without departing from its spirit and scope. For example, the carrier may comprise either a resin material, such as polyethylene terephthalate, which is impervious to gas and water vapor or a resin laminate comprising two or several different resin materials such as polyethylene (water impervious layer) and polycarbonate (gas tight layer). The present invention therefore is not deemed limited except as defined in the appended claims.

I claim:

1. A test patch used in proving the presence or absence of particular allergic contact eczemas comprising a test piece of liquid absorbing material, a carrier comprising a layer of liquid and gas impervious metal foil, and a plastic foil arranged between said test piece and said carrier, said test piece being attached to said carrier by heat sealing said plastic foil.

2. A test patch according to claim 1 further comprising a paper foil arranged on the side of said metal foil opposite the side to which said test piece is attached and a second plastic foil arranged between said paper foil and said metal foil, said paper foil being attached to said metal foil by heat sealing said second plastic foil.

3. A test patch according to claim 1 wherein said metal foil is made of aluminum.

References Cited UNITED STATES PATENTS 2,235,436 3/1941 Laub 128-2 3,212,495 10/1965 OsbOurn et a1. 1282 WILLIAM E. KAMM, Primary Examiner U.S. Cl. X.R. 128-268 (5/69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 a 5 5 126 Dated June 2 1970 Inventor(s) G S Fr'eger't It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below: r

Column 1, line 26, change "providing" to proving SI'G NED my 8 EALEU SEP 1 1970 (SEAL) Attest:

EdwardMFlewheblr. Amsfing offioer WILLIAM R. SGHUYLER, JR-

Comissionor or Patents I. 

